1. Field of the Invention
The present invention relates to a method and a control circuit for reducing an instantaneous startup current of a computer system. More particularly, the present invention relates to a method and a control circuit for reducing the instantaneous startup current of the computer system by decreasing a rotational speed of a fan device connected to the computer system.
2. Description of Related Art
Generally speaking, the amount of processors is varied in computer systems according to its usage and purpose. For instance, 1 to 2 processors are enough for the operation of a personal computer (PC), but it may need 8 to 16 processors for a computer server with more functionalities. Furthermore, a super computer which is used for specialized purposes such as nuclear weapon simulation, metrological applications, or gene engineering, may need hundreds or even thousands processors to satisfy the requirement of high computation efficiency. However, an enormous amount of heat will be generated by hundreds and millions of transistors in the processors during operating the computer system. And the stability of the computer system will be affected if the thermal issue is ignored. As a result, in order to protect components in the computer system, the generated heat must be sank properly.
A fan device which contains a number of fans is a crucial part to solve the thermal issue in today's computer system. The fan device can effectively lower internal temperature of the computer system and is relatively cheap to make. Along with the Hi-speed device and compact system evolvement, thermal issue becomes more and more critical to the stability of the computer system. The corresponding solution is to increase the speed or amount of fans. But in doing so, it makes the acoustic and instantaneous startup current issue even worse.
In conventional implementation, a PWM signal is used for controlling the fan device. Basically speaking, when the computer system is powered on, all of fans comprised in the fan device will be turned on at the same time with the fall speed. It is not only incurs a big surge current at a very short timeframe causing system unstable and even reset, but also cause a intolerable heavily acoustic issue.